1: thiophene With n-butyllithium in diethyl ether; hexane T=0°C; 1 h; 2: With zinc(II) chloride in diethyl ether; hexane T=0°C; 1 h; 3: 2,3,5-tribromothiophene With (1,1'-bis(diphenylphosphino)ferrocene)palladium(II) dichloride in diethyl ether; hexane T=20°C; regioselective reaction;

(1,1'-bis(diphenylphosphino)ferrocene)palladium(II) dichloride in diethyl ether 14 h;

NiCl2((PPh3)P)2 in tetrahydrofuran T=20°C; regioselective reaction;

1: 2,3,5-tribromothiophene With tetrakis(triphenylphosphine) palladium(0) in ethylene glycol dimethyl ether T=20°C; Suzuki coupling; 0.166667 h; Inert atmosphere; 2: dihydroxy-thien-2-ylborane With sodium hydrogencarbonate in ethylene glycol dimethyl ether T=40°C; Sukzuki coupling; Inert atmosphereReflux;

1: 2,3,5-tribromothiophene With tetrakis(triphenylphosphine) palladium(0) in ethylene glycol dimethyl ether T=20°C; Suzuki coupling; 0.166667 h; Inert atmosphere; 2: dihydroxy-thien-2-ylborane With sodium hydrogencarbonate in ethylene glycol dimethyl ether Suzuki coupling; 6 h; RefluxInert atmosphere;

1: 2,5-di(2-thienyl)-3-bromothiophene With n-butyllithium in diethyl ether T=15°C; Metallation; 1 h; 2: chloro-diphenylphosphine in diethyl ether T=20°C; Substitution; 0.5 h; Further stages.;

water; magnesium Multistep reaction;

1: 80 percent / 24 h / Heating 2: 74 percent / KOH / toluene; methanol / 20 h / Heating View Scheme